MSP430-GCC-OPENSOURCE: Printf format string length modifier "hh" not implemented in newlib

At present, macro PRIu8 resolves to "hhu", which does not seem to be supported by newlib's printf() implementation.

The same holds valid for the other PRI*8 macros. _intsup.h defines macro __INT8 to "hh". I guess this is technically correct, as "hh" should be correct for types of width CHAR_BITS, but it breaks in conjunction with newlib.

A quick search has shown that this problem comes up on other platforms as well:

Regression with printf 8-bit format macros (narkive.com)

inttypes.h macro PRIu8 generates wrong format string on cortex m0 · Issue #70 · platformio/platform-atmelsam · GitHub

I realise newlib's printf() has a trimmed-down feature-set as opposed to the POSIX version and may not support "hh" length modifiers for that specific reason. In this case, I propose to have macro __INT8 resolve to "h" on the MSP430 platform. This may not be POSIX compliant, but neither is the intended recipient at present.